Actions Achieve Critical BARDA Milestone; Company Now Eligible for
$20.5 Million Payment

NEW YORK--(BUSINESS WIRE)--
SIGA Technologies, Inc. (SIGA) (OTCMKTS:SIGA), a company specializing in
the development and commercialization of solutions for serious unmet
medical needs and biothreats, announced that it has received approval
from its Data Safety Monitoring Board (DSMB) to complete enrollment in
the second and final cohort of healthy subjects for the Phase III
clinical study for its lead drug candidate, TPOXX™ (tecovirimat), for
the treatment of orthopoxvirus infections. This determination was based
on review of safety data from the first 125 participants in the final
cohort. The final cohort of this Phase III study is being conducted at
eleven approved clinical investigation sites in a total of approximately
380 subjects.

The initial Phase III cohort of 40 subjects in this trial was completed
in 2015 without any reports of serious adverse events. Since TPOXX™
(tecovirimat) is being developed under the FDA "Animal Rule," there are
only safety and not efficacy endpoints in this clinical trial. This
Phase III study is wholly funded by the Biomedical Advanced Research and
Development Authority (BARDA).

SIGA also announced that it has submitted its final pivotal animal study
reports to the Food and Drug Administration (FDA). As a result of both
the DSMB decision and the submission of the FDA animal final study
reports, SIGA is eligible for a milestone payment from BARDA of $20.5
million.

SIGA anticipates submitting the complete New Drug Application (NDA) for
TPOXX™ by the end of 2017.

ABOUT SIGA TECHNOLOGIES, INC.

We are a company specializing in the development and commercialization
of solutions for serious unmet medical needs and biothreats. Our lead
product is Tecovirimat, TPOXX™, also known as ST-246®, an orally
administered antiviral drug that targets orthopoxviruses.
While TPOXX™ is not yet approved as safe and effective by the U.S. Food
& Drug Administration, it is a novel small-molecule drug that is being
delivered to the Strategic National Stockpile under Project BioShield.
For more information about SIGA, please visit SIGA's web site at www.siga.com.

FORWARD-LOOKING STATEMENTS

This press release contains certain "forward-looking statements" within
the meaning of the Private Securities Litigation Reform Act of 1995, as
amended, including statements relating to the effect of the loss of our
litigation with PharmAthene, Inc., our ability to raise the funds
necessary to satisfy the judgment arising from such loss and the effects
of our chapter 11 bankruptcy case on our future business and ability to
raise debt or equity financing. Such forward-looking statements are
subject to various known and unknown risks and uncertainties and SIGA
cautions you that any forward-looking information provided by or on
behalf of SIGA is not a guarantee of future performance. SIGA's actual
results could differ materially from those anticipated by such
forward-looking statements due to a number of factors, some of which are
beyond SIGA's control, including, but not limited to, (i) the risk that
potential products that appear promising to SIGA or its collaborators
cannot be shown to be efficacious or safe in subsequent pre-clinical or
clinical trials, (ii) the risk that SIGA or its collaborators will not
obtain appropriate or necessary governmental approvals to market these
or other potential products, (iii) the risk that SIGA may not be able to
obtain anticipated funding for its development projects or other needed
funding, including from anticipated governmental contracts and grants,
(iv) the risk that SIGA may not complete performance under the
Biomedical Advanced Research Development Authority (BARDA) Contract on
schedule or in accordance with contractual terms, (v) the risk that SIGA
may not be able to secure or enforce sufficient legal rights in its
products, including intellectual property protection, (vi) the risk that
any challenge to SIGA's patent and other property rights, if adversely
determined, could affect SIGA's business and, even if determined
favorably, could be costly, (vii) the risk that regulatory requirements
applicable to SIGA's products may result in the need for further or
additional testing or documentation that will delay or prevent seeking
or obtaining needed approvals to market these products, (viii) the risk
that one or more protests could be filed and upheld in whole or in part
or other governmental action taken, in either case leading to a delay of
performance under the BARDA Contract or other governmental contracts,
(ix) the risk that the BARDA Contract is modified or canceled at the
request or requirement of the U.S. government, (x) the risk that the
volatile and competitive nature of the biotechnology industry may hamper
SIGA's efforts to develop or market its products, (xi) the risk that the
changes in domestic and foreign economic and market conditions may
affect SIGA's ability to advance its research or may affect its products
adversely, (xii) the effect of federal, state, and foreign regulation,
including drug regulation and international trade regulation, on SIGA's
businesses, (xiii) the risk that our chapter 11 bankruptcy case may make
it more difficult to obtain additional financing, (xiv) the risk that
our internal controls will not be effective in detecting or preventing a
misstatement in our financial statements, (xv) the risk that some
amounts received and recorded as deferred revenue may someday be
determined to have been more properly characterized as revenue when
received, (xvi) the risk that some amounts received and recorded as
deferred revenue ultimately may not be recognized as revenue, and (xvii)
the risk associated with the loss of our appeal to the Delaware Supreme
Court in our litigation with PharmAthene, Inc., including, the risks
related to a failure to satisfy the judgment arising from the loss of
the litigation with PharmAthene, Inc More detailed information about
SIGA and risk factors that may affect the realization of forward-looking
statements, including the forward-looking statements in this press
release, is set forth in SIGA's filings with the Securities and Exchange
Commission, including SIGA's Annual Report on Form 10-K for the fiscal
year ended December 31, 2015, and in other documents that SIGA has filed
with the SEC. SIGA urges investors and security holders to read those
documents free of charge at the SEC's web site at http://www.sec.gov.
Interested parties may also obtain those documents free of charge from
SIGA. Forward-looking statements are current only as of the date on
which such statements were made, and except for our ongoing obligations
under the United States of America federal securities laws, we undertake
no obligation to update publicly any forward-looking statements whether
as a result of new information, future events, or otherwise.